A fundamental problem faced by the visual system is providing information about the 3d environment from the 2d retinal images. Perhaps the most precise source of information arises from the fact that the tw( eyes have different vantage points. This means that images on the two retinae are not identical. Th_ differences between the locations of matching features on the retinae are binocular disparities and the abilit_ to perceive depth from these disparities is stereopsis. Investigations of inferring 3d layout from disparity fall into two general categories: 1) the estimation of disparity from the retinal images and 2) the interpretation of the estimated disparity. Specific Aim 1 concerns disparity estimation and Specific Aims 2 and 3 concern disparity interpretation. In the experiments and modeling associated with Specific Aim 1, we will examine the spatial and chromatic properties of disparity-estimating mechanisms. We will, for example, determine whether the highest stereoresolution, the disparity-gradient limit, and the difference in stereo sensitivity with luminance as opposed to chromatic stimuli result from using a binocular-matching algorithm that provides piecewise-frontal estimates of the depth map. In some of these experiments, we will improve the optics of the eye and investigate the costs and benefits to stereo vision. In the experiments and modeling associated with Specific Aim 2, we will investigate whether disparity and texture slants signals are combined in a weighted sum (for estimating slant) and a difference (for assessing texture homogeneity). We will also examine how changes the reliability of disparity and texture signals affects these two processes. In the experiments associated with Specific Aim 3, we will study a widely experienced perceptual phenomenon: adaptation to the 3d distortions that result from horizontal magnification of one eye's image. We will try to pinpoint the adaptation mechanism and to determine whether subjects can adapt to two states simultaneously. We will also examine adaptation to a vertical magnification of one eye's image.